Decreasing ruminal methane production through enhancing the sulfate reduction pathway

Methane (CH(4)) production from ruminants accounts for 16% of the global greenhouse gas emissions and represents 2% to 12% of feed energy. Mitigating CH(4) production from ruminants is of great importance for sustainable development of the ruminant industry. H(2) is the primary substrate for CH(4) production in the processes of ruminal methanogenesis. Sulfate reducing bacteria are able to compete with methanogens for H(2) in the rumen, and consequently inhibit the methanogenesis. Enhancing the ruminal sulfate reducing pathway is an important approach to mitigate CH(4) emissions in ruminants. The review summarized the effects of sulfate and elemental S on ruminal methanogenesis, and clarified the related mechanisms through the impacts of sulfate and elemental S on major ruminal sulfate reducing bacteria. Enhancing the activities of the major ruminal sulfate reducing bacteria including Desulfovibrio, Desulfohalobium and Sulfolobus through dietary sulfate addition, elemental S and dried distillers grains with solubles can effectively decrease the ruminal CH(4) emissions. Suitable levels of dietary addition with different S sources for reducing the ruminal CH(4) production, as well as maintaining the performance and health of ruminants, need to be investigated in the future.